Well, do the same thing across the front. If you have to do ceiling, make all 3 ceiling. Like Daniel said, your imaging will be impossible if you split them up with some above and the center on the TV. Perhaps if there are ceiling speakers that can be angled a bit towards the couch, it would help. If you simply put down-firing speakers in the ceiling above the TV, the sound will not easily get to you. I don't know much about ceiling installs, though.

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